Varnished sheet material



Patented Oct. 20, 1942 VARNISHED SHEET MATERIAL Henry A. Lctteron,Schenectady, N. Y., assignor I to General Electric Company, acorporation of New York No Drawing. Application November 28, 1939,

Serial No. 806,521

1 Claim. (Cl. 117 161) This invention relates to varnished sheetmaterials and more particularly is concerned with flexible sheetmaterials, for example cloth, paper,

etc., varnished with an oil-modified alkyd resin (polyhydricalcohol-polybasic acid resin) the oily component of which is present inexcess of 50- per cent by weight and which has an iodine number notexceeding 90.

One of the very important qualities of varnished cloth and similarvarnished materials is the maintenance of flexibility even afterprolonged exposure to elevated temperatures. Previous attempts have beenmade to prepare these 7 formaldehyde coating compositions. In such casesthe alkyd resin is used merely to improve the plasticity and adhesiveproperties of the composition.

Ihave discovered that certain alkyd resins modified with at least 50 percent by weight of fatty oils or fatty acids of low iodine number, for

example non-drying oils and fatty acids thereof,

will form dry, strong, tough, adhesive films under heat or, in certaincases, even at room temperature in the absence of other modifying resinsor the like. This is surprising, since it is contrary to the theories ofoil-drying reactions and to previous experience in varnish making fromoils alone or from mixtures of oils and resins such as rosin, copal,etc. For a given oil length, I have observed that the rigidity of suchoil-modified alkyd resins is greatly decreased by the presence oflow-iodine number oils. The final rigidity is attained after acomparatively short bake and it remains practically unchanged even afterremarkably long exposure to elevated temperatures.

These observations and discoveries led to my further discovery thatvarnished sheet materials, for example varnished cambric, silk, paper,metal foils, etc., having outstanding resistance to heat and aging canbe produced by varnishing the sheet material with a varnish the base orprimary component of which is composed essentially of the resinousreaction product of polyhydric alcohol, polybasic carboxylic acid and amajor portion of a fatty substance the iodine number of which does notexceed 90. A fatty substance of, such iodine number yields a modifiedalkyd resin film that remains flexible even after long exposure to hightemperature and although the amount of fatty substance is in excess ofper cent by weight of the resin, nevertheless tough films of high filmstrength are obtained.

The fatty substance may be a fatty oil, a fatty acid, specifically afatty -oil acid, or mixture or fatty oil and fatty acid, the individualoil or acid having an iodine number not higher than 90. Mixtures ofdiflerent fatty oils or mixtures of diiIerent fatty acids, which oils oracids have an iodine number of 90 or lower, may be used if desired; or,the fatty substance may be a mixture of fatty materials having an iodinenumber higher than 90 with a different fatty material below 90 in iodinenumber, the proportions being so adjusted that the iodine number of themixed fatty materials does not exceed 90. Sucha mixture of fattymaterials may be mixed fatty oils of high andlowiodine number or mixedfatty acids of high and low iodine number; or, it may be a mixture offatty oil or oils of high iodine number with a fatty acid or acids oflow iodine number, or a mixture of high iodine number fatty acid oracids with a low iodine number fatty oil or oils.

In most cases I use an alkyd resin modified with from 50 to 85 per centby weight of a fatty oil, preferably from to '70 per cent, having aniodine number somewhat less than 90, for example about to 88 as theupper limit. In certain cases fatty substances having little, if any,unsaturation may be employed, but ordinarily I do not use alkyd resinsmodified with fatty substance having an iodine number much less thanabout 5.

The varnished, flexible sheet materials of this invention haveexceptional resistance to aging both at normal and at elevatedtemperatures. These remarkable aging properties are obtained withoutdecreasing the toughness of the resin film or lengthening the bakingcycle. The coated materials are smooth-surfaced and have excellentresistance to oil, moisture and abrasion. The resin film is hard,flexible, tough, pale in color, and has much less odor than the usualalkyd resin films. i

In order that those skilled in this art better may understand how thepresent invention may be carried into effect, the following specificexamples are given for purpose of illustration:

Example 1 Parts by weight Cocoanut oil 59.5 Glycerol 16.6 Maleicanhydride 23.6 Calcium oxide 0.3

The oil, glycerol and lime (esterification catalyst) are placed in akettle equipped with a reflux condenser and stirrer and heated toapproximately 250 C. for about 1 hour. The tempera- Maleic anhydridecent by weight of solids. Driers are added and, w

the resulting varnish is applied to cloth oro'ther flexible material inaccordance with conventional practice. The coated article is usuallybaked. to harden the coating.

Emample 2 Parts by weight Soya bean oil fatty acids .i 26.5 Cocoanut oilfatty acids 2J5 Pentaerythritol 214.2 Phthalic anhydride 2.8.6

All the ingredients are placed in akettle and heated for one hour atapproximately 190 to 200 C. The temperature is raised to about 235to-250 C. and cooking continued .until a resin with an acid number ofabout 3 to 5 is obtained. 'I'he'finished resin is handled in the samemanner as described under Example 1.

Example 3 Parts by weight Cocoanut oil fatty acids 5 1.3 Pentaerythritol211.9 Phthalic anhydride 25.6

All the ingredients except the maleic anhydride are placed in a kettleand heated at approximately 190 to 200 C. until a clear pill isproduced. The maleic anhydride is added and cooking iscontinued atapproximately 235 to 250 C. until a resin having an acid number of about5 to 8 is obtained. Varnishes and coated fabrics, metal foils, etc., aremade from this resin in substantially the sam manner as described underExample 1.

One unexpected result from the use of resins such as herein described inthe production of varnishes and varnished materials is the improvementin film-forming properties which are obtained. For example, a non-dryingoil such as cocoanut oil having incorporated therein a metallic driermay be spread into a film and held for four days at 150 C. withoutsolidifying. In marked contrast a resin such as described under Example1, with which has been mixed 9. small amount of a suitable drier, willform a solid nontacky film upon being heated for less than one hour at150 C.

Another unexpected result is the rapidity with which theherein-described resins may be converted to solid films at elevatedtemperatures. Textile materials such as cotton, wool, linen, silk, glassfibers, synthetic fiber such as superpolyamide fibers, etc., in woven,felted or other form, therefore can be coated or coated and impregnatedwith varnishes produced as set forth under the illustrative examples,and the applied film quickly solidified under heat to a hard, tough,moistureand abrasion-resistant, substantially permanently flexiblecoating. Also, by suitable selection of oils anddriers in producingtheresin and varnish, resin films having air-drying properties may beobtained.

It is of course understood that the present invention is not limited tothe production of sheet materials varnished with resinous compositionsformed of the specific ingredients named in the illustrative examples.For instance, other polybasic carboxylic acids or anhydrides may be usedin forming the alkyd resin, in addition to those mentioned above and inlieu of, or in addition to, the polyhydric alcohols, lycerol andpentaerythritol, named in the illustrative examples, I may use similarpolyhydric alcohols.

.' As illustrative of fatty oils and fatty acids which, as commerciallyavailable, usually have iodine numbers of 90 or less and which may beused alone or mixed in producing .the oil-modified alkyd resins employedin carrying the present invention into eflfect, I mention the followingcommonly classified as vegetable fats:

Approximate iodine number Fatty 011 acids 5-10 6-10 8 l2 aim '49-59 53Cottonseed stearin (gossypium). 86-90 90 It will be understood by thoseskilled in the art that the iodine numbers of the oils and fatty acidsmentioned above may vary somewhat, depending, for example, upon theparticular source of the raw material and the extent to which thematerial has been purified. The fatty oils and fatty acids used inproducing the hereindescribed oil-modified alkyd resins are bought onspecification, the acceptable-fatty substances in all cases having aniodine number not exceeding 90.

Of the above mentioned commerciall available fatty oils and fatty acids,known as vegetable fats, the cocoanut oil or acids form varnished sheetmaterials which are outstanding in their flexibility and lack of odorwhile the cottonseed stearin is preferred from the cost standpoint.Those cottonseed products of this type so prepared as to have an iodinevalue below 90 are used. When a single oil or 'acid is used; thecottonseed stearin is highly satisfactory for accomplishing the purposesof this invention. The resins prepared from all of the above vegetablefats I give comparatively odorless films.

A suitable resin for making a varnish and varnished sheet material ofsuperaging characteristics also may be produced by incorporating intothe resin low-iodine-number fatty oils and (or) fatty acids, such asabove mentioned, admixed with fatty oils and (or) fatty acids having aniodine number materially over 100, examples of which latter are:

In all cases the proportions of fatty materials of high and low iodinenumber are so adjusted that the iodine number of the mixture does notexceed 90. The dehydrated castor oil is to be distinguished fromordinary castor oil. The latter, frequently used in alkyd resinmodification,

readily dehydrates during resin formation to form the more unsaturatedproduct.

The method of combining the components of the resin may be varied inmany ways, as is now well understood in the alkyd resin art.

In making the varnish the resinous composition may be thinned with anysuitable solvent, for example turpentine, coal tar solvents, petroleumhydrocarbon solvents, etc. Any suitable drier and in any convenient formmay be used, for example, the naphthenates, linoleates or resinates ofmetals such as calcium, manganese, lead, cobalt, zinc and iron. Thepercentage of drier required may be varied to suit manufacturingrequirements for producing dry varnished sheet material in a minimum oftime. Or, in some cases, the drier may be omitted. If desired, dyes maybe incorporated into the resin or into the varriish in order to obtaintransparent colored film. Also, if desired, the usual. paint pigmentsmay be introduced into the resin, as by grinding the componentstogether, to form compositions yielding opaque, colored films of goodflexibility.

The liquid coating composition or varnish is applied to the sheetmaterial to, be coated by brushing, sprinkling, spraying or, preferably,by

immersion means and under temperature and other conditions commonlyemployed. Upon heating the varnished sheet material at a temperature ofabout 1105C. or thereabove, the sol-- vent is evaporated and a varnishedarticle of ex-' ceptional aging characteristics, good slip, and with ahard, tough, adhering resin film thereon is obtained. I

In testing the heat and age resistance of the varnished sheet material asample of the same is heated in a suitable oven at a temperature ofabout 125 C. The heated sample is tested for cracking of the resin filmat the end of varying 0 periods of time. This is done by wrapping thesample around a mandrel of suitable size, for example, 0.048 inch indiameter, and noting whether or not the resin film has cracked.

As illustrative of the way the resistance to gin is affected by theiodine number of the fatty substance used in the preparation of theresin, the following data are given:

The series 1 resins were prepared from Parts by weight Boys bean oilfatty acids. Cottonseed oil fatty acids. 71 Pantaerythritol 16 Phthalieanhydride 9 Maleic anhydride 4 4 The series 2 resins were prepared fromParts by shi Cottonseed oil fatty acids 62 Soya bean oil fatty acids 31Cocoanut oil fatty acids. 30 Pentaerythritol 18 20 Phthalic anhydride.l8 l0 Maleic anhydride 2 0 Resins of thetype herein described areparticularly useful in the preparation of materials such as theso-called oiled silk" where extreme flexibility over a long timeisrequired, together with toughness of him, light color and freedom fromodor. Silk treated with the described coating compositions is especiallysuitable for use as covers for umbrellas, in the manufacture ofraincoats, as covers for food containers, and for many otherapplications. The pigmented varnishes also may be used in themanufacture of so-called oil cloth," patent leather, and

and assigned to the same assignee as the present invention.

The term acid" as used broadly in the appended claim is intended toinclude within its meaning the anlrvdride of the acid.

whatliclaimasnewanddesiretosecureby Letters Patent of the United Statesis:

A flexible, odorless, heatand age-resistant, varnished fabric materialconsisting of fabric material coated and impregnated with a baked filmor a compomtion composed of a polyhydric alcohol containing at leastthree hydroxyl groups, a mixture of phthalic anhydride and maieicanhydride, and -70 per cent by weight of cottonseed stearin having aniodine number below 90.

- HENRY A. IEI'IERON.

